ES2395213T3 - Intravascular occlusion devices guided by a percutaneous catheter - Google Patents

Abstract

The present invention provides a method of forming a medical device and medical devices which can be formed in accordance with the method. In one embodiment, the method includes the steps of a) providing a metal fabric formed of a plurality of strands formed of a metal which can be heat treated to substantially set a desired shape; b) deforming the metal fabric to generally conform to a surface of a molding element; c) heat treating the metal fabric in contact with the surface of the molding element to substantially set the shape of the fabric in its deformed state; and d) removing the metal fabric from contact with the molding element. The resulting metal fabric will define a medical device which can be collapsed for passage through a catheter or the like for deployment in a channel of a patient's body. Medical devices made in accordance with this method can have varying structures.

Description

Intravascular occlusion devices guided by a percutaneous catheter

BACKGROUND OF THE INVENTION

I. FIELD OF THE INVENTION

[0001] The present invention relates, in general, to intravascular devices for treating certain medical conditions and, more particularly, it relates to intravascular occlusion devices for the treatment of Atrial Septal Defects (hereinafter ASD) and Permeable Arterious Ductus (hereinafter PDA). The devices made according to the invention are particularly suitable for delivery, by means of a catheter or the like, to a remote location in a patient's vascular system or in analogous vessels within a patient's body.

II. DESCRIPTION OF THE STATE OF THE TECHNIQUE

[0002] A wide variety of intravascular devices are used in various medical procedures. Certain intravascular devices, such as catheters and guidewires, are generally used simply to deliver fluids or other medical devices to specific positions within a patient's body, such as a selective site within the vascular system. Other devices, often more complex, are used to treat specific conditions, such as devices used to eliminate vascular occlusions or to treat septal defects and the like.

[0003] In certain circumstances, it may be necessary to occlude a patient's vessel, for example, to stop the flow of blood through an artery to a tumor or other lesion. Currently, this is commonly achieved by simply inserting, for example, Ivalon particles (trade name of vascular occlusion particles) and short sections of helical springs at a desired location within a vessel. These "embolization agents" will eventually become lodged in the vessel, frequently floating downstream from the site where they are released before blocking the vessel. This procedure is often limited in its usefulness, partly due to the inability to accurately position the embolization agents.

[0004] Balloon-type catheters, similar to those disclosed by Landymore et al. Have been used by U.S. Pat. . 4,836,204, to temporarily occlude a septal defect until the patient is sufficiently stabilized for open heart surgical techniques. Balloon catheters, decoupling, have also been used to block patient vessels. When such a catheter is used, an expandable balloon is carried at a distal end of a catheter. When the catheter is guided to the desired position, the balloon is filled with a fluid until it substantially fills the vessel and becomes lodged therein. Resins, such as an acrylonitrile, which will harden inside the balloon can be used to permanently fix the size and shape of the balloon. The balloon can then be separated from the end of the catheter and left in place.

[0005] However, this balloon embolization is also prone to certain security problems. For example, if the balloon is not filled enough, it will not be firmly attached to the vessel and can drift or drift downstream inside the vessel to another position, much like the loose embolization agents mentioned above. In order to avoid this problem, doctors can overfill balloons; It is not uncommon for balloons to break and release the resin in the patient's bloodstream.

[0006] Embolization devices, filters and mechanical hatches have been proposed in the past, some of which are disclosed by King et al., U.S. Pat. . 3,874,388; Das, U.S. Patent . 5,334,217; and Marks, U.S. Patent . 5,108,420. These devices are preloaded into the introducer or administration catheter and are not easily chargeable by the doctor. In addition, during the deployment of these devices, recapture by the carrier catheter is difficult, if not impossible, thereby limiting the effectiveness of these devices.

[0007] WO 97/31672, which is a state of the art under Article 54 (3) EPC, discloses a self-expanding cardiovascular occlusion apparatus in which additional fibers are installed in the core of the device.

[0008] In addition, although some of these devices prove to be effective occluders, they also tend to be quite expensive and with long manufacturing times. For example, some intravascular blood filters are formed of a plurality of specially shaped legs that are adapted to fill the vessel and dig into the vascular walls. In the manufacture of most such filters, the legs must be individually formed and then laboriously joined together, often requiring hand coupling, to assemble the final filter. This not only requires significant skilled labor, and therefore increases the costs of such devices, but the fact that each item must be made by hand tends to make quality control more difficult. This same difficulty and manufacturing cost are not limited to such filters, but are also experienced in many other intravascular devices.

[0009] By using these devices to occlude an ASD, the pressure and, therefore, the possibility of displacement of the device increases with the square of the size of the communication. Consequently, these devices must have a very large retention skirt. Often, the position of the ASD dictates the size of the retention skirt. Therefore, there is a need for an ASD occluder that can be manufactured with a relatively small retention skirt. Also, the shape of state-of-the-art devices (for example squares, triangles, pentagons, hexagons and octagons) requires a larger contact area, with corners extending to the free wall of the atrium. Each time the atrium contracts (approximately 100,000 times per day), the internal threads of state-of-the-art devices bend, creating fractures of structural fatigue in approximately 30 percent of all cases. In addition, the above devices require a French 14-16 introduction catheter, making it impossible to treat children affected with congenital defects with these devices.

[0010] Accordingly, it would be advantageous to provide a reliable embolization device, which at the same time is easy to deploy by means of a French 6-7 catheter, and that can be accurately placed in a vessel. It would also be desirable to provide a recoverable device, for deployment in a vessel in a patient's body, which is both economical and produces consistent reproducible results.

SUMMARY OF THE INVENTION

[0011] The invention provides a folding medical device as defined in claim 1.

[0012] The present invention provides a reliable intravascular occlusion device, which can be formed to treat, for example, Atrial Septal Defects (hereinafter ASD) and Permeable Arterial Ductus (hereinafter PDA). By forming these intravascular devices, from an elastic metallic fabric, a plurality of elastic filaments are disposed, the strands being formed by braiding to create an elastic material that can be heat treated to substantially fix a desired shape. This braided fabric is then deformed to generally conform to a molding surface of a molding element, and the braided fabric is heat treated in contact with the surface of the molding element at an elevated temperature. The time and temperature of the heat treatment are selected to substantially fix the braided fabric in its deformed state. After heat treatment, the fabric is removed from contact with the molding element and will substantially retain its shape in the deformed state. The braided tissue so treated defines an expanded state of a medical device that can be deployed through a catheter into a channel in a patient's body.

[0013] Additional embodiments of the present invention also provide specific forms for medical devices that can be made to treat predetermined medical procedures. Such devices of the invention are formed of a braided metal fabric and have an expanded configuration and a folded configuration. In use, a guide catheter can be positioned in a canal in a patient's body, and advanced to place the distal end of the adjacent catheter in a treatment site, to treat a physiological condition. A medical device, formed in a predetermined manner and made in accordance with the process described above, can be folded and inserted into the lumen of the catheter. The device is driven along the catheter until it exits the distal end, whereby, due to its memory property, it will tend to return substantially to its expanded state adjacent to the treatment site. According to a first of these embodiments, a generally elongated medical device has a generally tubular middle part and a pair of expanded diameter parts, with an expanded diameter part positioned at either end of the middle part. In another embodiment, the medical device is generally bell-shaped, with an elongated body having a first sharp end and a second major end, the second end presenting a tissue disc that will be oriented, generally, perpendicular to an axis of a channel when deployed within it.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014]

Figures 1A and 1B each describe a metallic fabric suitable for use in the invention;

Figure 2A is a side view, with the parts removed, of a molding element having a section of a metal fabric suitable for use in the formation of a medical device according to the invention;

Figure 2B is a perspective view, with the parts broken, of the molding element shown in Figure 2A;

Figure 3A is a perspective view, showing the molding element of Figures 2A and 2B in a partially assembled state;

Figure 3B is a close view of a part of the highlighted area of Figure 3A, showing the compression of the metal fabric in one of the cavities of the molding element;

Figure 4 is a sectional view, showing the molding element of Figures 2A and 2B in an assembled state, and with the metal fabric formed within the cavities of the molding elements;

Figure 5A is a side view of a medical device;

Figure 5B is an end view of the medical device;

Figures 6A-6C are a side view, an end view and a perspective view, respectively, of a medical device;

Figure 7 is a sectional side view of a molding element suitable for forming the medical device shown in Figures 6A-6C;

Figure 8 is a schematic illustration, showing the device of Figures 6A-6C deployed in a central bridge of a patient's vascular system;

Figure 9A is a side view of a medical device;

Figure 9B is an end view of the medical device shown in Figure 9A;

Figure 10A is a side view of a molding element, suitable for forming the embodiment of Figures 9A and 9B;

Figure 10B is a sectional view of another molding element, suitable for forming the embodiment of Figures 9A and 9B;

Figure 10C is a sectional view of another molding element, suitable for forming the embodiment of Figures 9A and 9B;

Figure 11 is an enlarged partial sectional view of an ASD device, shown stretched and partially extending out of the lumen of a carrier catheter;

Figure 12 is a partial sectional view of a PDA device, of the type shown in Figures 6a-6c, wherein the PDA device is shown stretched and partially extending out of the lumen of a carrier catheter;

Figure 13 is an enlarged side elevation view of an ASD device, shown in its preformed configuration;

Figure 14 is a side elevational view of the ASD device of Figure 13, shown slightly stretched and filled with polyester fibers;

Figure 15 is a partial side elevational view in section of the ASD device of Figure 13, shown stretched and filled with polyester fibers;

Figure 16 is an elevational and partial sectional view of the ASD device of Figure 13, shown positioned within an ASD of a patient's heart;

Figure 17 is an enlarged side elevation view of an ASD device according to the invention, shown in its preformed configuration; Y

Figure 18 is a side elevation view of the ASD device of Figure 16, shown stretched and filled with polyester fibers.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] The present invention provides an intravascular occlusion device, directed by a percutaneous catheter, for use in bridges in patient bodies, such as vascular channels, urinary tracts, bile ducts and the like. When forming a medical device by means of the method of the invention, a metallic fabric 10 is arranged. The fabric is formed of a plurality of filaments with a predetermined relative orientation between the filaments. Figures 1A and 1B illustrate two examples of metal fabrics that are suitable for use in the method of the invention.

[0016] In the fabric of Figure 1A, the metallic filaments define two sets of essentially parallel filaments, generally helical, the filaments of a set having a "hand"; that is, a direction of rotation opposite to that of the other game. This defines a generally tubular fabric, known in the textile industry as tubular braid. Such tubular braids are well known in textile techniques and find some applications in the field of medical devices such as tubular tissues, for example to reinforce the wall of a guide or diagnostic catheter. Since such braids are well known, they do not need to be explained here extensively.

[0017] The passage of the filaments of yarn (ie, the defined angle between the turns of the yarn and the axis of the braid) and the advance of the fabric (ie, the number of turns per unit length) can be adjusted as desired for a particular application. For example, if the medical device to be formed is to be used to occlude the channel in which it is placed, the passage and advancement of the tissue will tend to be greater than if the device simply seeks to filter body fluid that passes through it.

[0018] For example, by using a tubular braid, such as that shown in Figure 1, to form a device such as that illustrated in Figures 5A and 5B, a tubular braid about 4 mm in diameter, with a pitch of about 50 ° and an advance of about 74 (per linear inch), would seem suitable for manufacturing devices used to occlude channels of the order of about 2 mm to about 4 mm inside diameter, as detailed below in relation to the realization of the Figures 5A and 5B.

[0019] Figure 1B illustrates another type of tissue that is suitable for use in the method of the invention. This fabric is a more conventional fabric and can take the form of a knitted, knitted or similar flat sheet. In the woven fabric shown in Figure 1B there are also two sets 14 and 14 'of filaments, generally parallel, a set of filaments oriented at an angle, for example generally perpendicular (with a plot of about 90 °), with respect to the another game. As indicated, the passage and advance of this fabric (or, in the case of a knitted fabric, the advance and the pattern of the point, for example plain or double point) can be selected to optimize the desired properties of the device. final doctor

[0020] The wire filaments of the metallic fabric used in the present method should be formed of a material that is both elastic and can be heat treated to substantially fix a desired shape. Materials that are suitable for this purpose include a cobalt-based low thermal expansion alloy, known in the field of the invention as Elgeloy, high strength and high temperature "super alloys" based on nickel commercially available from Haynes International under the trade name Hastelloy; heat treatable alloys, based on nickel, sold under the name Incoloy by International Nickel; and a number of stainless steels of different grades. The important factor in choosing a suitable material for the threads is that the threads retain an adequate amount of deformation induced by the molding surface (as described below) when subjected to a predetermined heat treatment.

[0021] A class of materials that meet these requirements are so-called shape memory alloys. Such alloys tend to have a temperature-induced phase change, which will cause the material to have a preferred configuration that can be set by heating the material above a certain transition temperature, to induce a change in the phase of the material. When the alloy cools again, the alloy will "remember" the way it was during heat treatment and will tend to assume that configuration unless it is prevented from doing so.

[0022] A shape memory alloy, particularly preferred for use in the present method, is nitinol, an approximately stoichiometric alloy of nickel and titanium, which may include other smaller amounts of other metals to achieve the desired properties. NiTi alloys, such as nitinol, including the appropriate compositions and handling requirements, are well known in the art, so they do not need to be discussed here in detail. For example, U.S. Pat. 5,067,489 (Lind) and 4,991,602 (Amplatz et al.) Explain the use of NiTi alloys with shape memory in guidewires. Such NiTi alloys are preferred, at least in part, because they are commercially available and more is known about the handling of such alloys than of other known shape memory alloys. NiTi alloys are also very elastic - they are said to be "superelastic" or "pseudo-elastic." This elasticity will help a device of the invention return to an expanded configuration preset for deployment.

[0023] When forming a medical device according to the invention, a piece of an appropriate size of the metallic fabric is cut, from the larger piece of tissue that has been formed, for example, braiding filaments of yarn to form a long tubular braid . The dimensions of the piece of tissue to be cut will depend, in large part, on the size and shape of the medical device to be formed therefrom.

[0024] When cutting the fabric to the desired dimensions, make sure that the fabric does not fray. In the case of tubular braids formed of NiTi alloys, for example, the individual wire filaments will tend to return to their thermally fixed configuration unless prevented. If the braid is heat treated to fix the filaments in the braided configuration, they will tend to remain in the braided form and only the ends will fray. However, it may be more economical to simply form the braid without treating the braid thermally, since the tissue will be heat treated again when forming the medical device, as indicated above.

[0025] In such untreated NiTi fabrics, the threads will tend to return to their unbraided configuration and the braid can be undone quite quickly, unless the ends of the braid section cut to form the device are held together. One method that has proven useful to prevent the braid from falling apart is to hold the braid with some fasteners in two locations, and cut the braid to leave a stretch of the braid with some fasteners (15 in Figure 5A) in one and the other extreme, thus effectively defining an empty space in a sealed stretch of tissue. These fasteners 15 will hold the ends of the cut braid together and prevent the braid from falling apart.

[0026] Alternatively, it can be welded with brazing, soft welding or contribution, or together fixing the ends of the desired section together (for example, with a biocompatible cementitious organic material), before cutting the braid. Although it has been shown that welding with NiTi alloys with hard and soft soldering is quite difficult, the ends can be welded, for example, by spot welding with a laser welder.

[0027] The same problems arise when a flat sheet of fabric is used as the woven fabric shown in Figure 1B. With this tissue, the tissue can be folded over itself to form a recess or depression and the tissue can be held with fasteners around this recess to form an empty bag (not shown) before the tissue is cut. If it is desired to keep the fabric in a generally flat configuration, it may be necessary to weld the crossings of the wires adjacent to the periphery of the desired piece of fabric before cutting that piece of the larger sheet. Connecting the ends of the wires together will prevent the tissues formed of alloys with memory without treatment and the like from falling apart during the formation process.

[0028] Once a piece of metal fabric with the appropriate size has been obtained, the fabric is deformed to generally conform to a surface of a molding element. As will be seen more fully from the following explanation in relation to Figures 2-10, thus deforming the fabric will reorient the relative positions of the metal fabric threads, from their initial order to a second reoriented configuration. The shape of the molding element should be selected to deform the tissue to substantially the shape of the desired medical device.

[0029] The molding element may be a single piece, or it may be formed by a series of molding pieces that together define the surface to which the fabric will generally fit. The molding element can be placed within a space included by the fabric or it can be external to such space, or it can even be both inside and outside such space.

[0030] In order to illustrate an example of how such a mold can be configured and how it can be used according to the method of the invention, reference will be made to Figures 2-5. In Figures 2-4, the molding element 20 is formed by a number of separate pieces that can be joined together to complete the molding element 20. By using such a multi-piece molding element, the mold can be mounted around the section of cutting the fabric 10, thereby deforming the fabric to generally conform to the desired surface (or surfaces) of the molding element.

[0031] In the molding element illustrated in Figures 2-4, the metal web 10 is deformed to generally conform to a surface of the molding element 20, the molding element comprising a central section 30 and a pair of end plates 40. Referring first to the central section 30, the central section is desirably formed by opposite halves 32, 32 that can be separated from each other in order to introduce the metallic fabric 10 into the mold. Although these two halves 32, 32 are shown in the drawings as being completely separated from each other, it should be understood that these halves may be interconnected, as by means of a hinge or the like, if desired. Each of the opposite halves of the molding element 20, shown in the drawings of Figures 2 and 3, includes a pair of opposite semicircular recesses on each side of a crest defining a generally semicircular opening. When the two halves are assembled to form the device, as best seen in Figure 3, the semicircular openings in the opposite halves 32, 32 fit together to define a generally circular formation opening 36 that passes through the central section 30. Similarly, the semicircular recesses in the two halves together form a pair of generally circular central recesses 34, one of such recesses being arranged on each face of the central section.

[0032] The shape and general dimensions of the central section can be varied as desired; it is generally the size of the central recesses 34 and the formation opening 36 that defines the size and shape of the middle area of the finished device, as explained below. If so desired, each half 32 may be provided with a manually apprehensible projection 38. In the embodiment shown in the drawings, this projection 38 is disposed in a position located away from the abutment faces of the respective halves. Such manually apprehensible projection 38 will simply allow an operator to more easily join the two halves to define the recesses 34 and the formation opening 36.

[0033] The central section is adapted to cooperatively connect a pair of end plates 40 to form the desired device. In the embodiment shown in Figures 2 and 3, the central section 30 has a pair of external flat faces 39 each of which is adapted to be connected by an internal face 42 of one of the two end plates 40. Each end plate It includes a compression disc 44 which generally extends laterally into the inner face 42 of the end plate. This compression disc 44 should be sized to allow it to be received within one of the central recesses 34, on either side of the central section 30. For reasons explained more fully below, each compression disc 44 includes a cavity 46 to receive one end of the section of the metallic fabric 10.

[0034] One or more channels 48 can also be arranged to receive bolts and the like through each end plate and through the central section 30. By passing bolts through these channels 48, one can assemble the molding element 20 and retain the metallic fabric in the desired shape during the heat treatment process, as described below.

[0035] By using the molding element 20 shown in Figures 2-4, a section of the metal fabric 10 can be positioned between the opposite halves 32 of the central section 30. In the drawings of the molding element 20 of the figures 2 -4, the metallic fabric 10 is a tubular braid as illustrated in Figure 1A. A sufficient section of the tubular braid should be provided to allow the tissue to fit the molding surface, as explained below. Also, as indicated above, care should be taken to fix the ends of the strands of yarn that define the tubular braid in order to prevent the metallic tissue from falling apart.

[0036] A central portion of the metal braid section can be placed within one of the two halves of the forming opening 36 and the opposite halves 32 of the central section can be joined to abut each other, to contain a central part of the metal braid inside the central forming opening 36 through the central section.

[0037] The tubular braid will tend to have a relaxed natural diameter that is defined, in large part, when the tubular braid is formed. Unless the tubular braid is otherwise deformed, when the filaments of yarn are in their relaxed state they will tend to define a generally hollow tube with the predetermined diameter. The outer diameter of the relaxed braid can be, for example, about 4 mm. The relative size of the formation opening 36 in the central section 30 of the molding element and the relaxed natural outer diameter of the tubular braid can be varied as desired to achieve the desired shape of the medical device in formation.

[0038] In the embodiment shown in Figures 2 and 3, the internal diameter of the forming opening 36 is optimally slightly smaller than the relaxed natural outer diameter of the tubular braid 10. Therefore, when the two halves 32, 32 are assembled to form the central section 30, the tubular braid 10 will be compressed slightly into the forming opening 36. This will help ensure that the tubular braid conforms to the inner surface of the forming opening 36, which defines a part of the molding surface of the molding element 20.

[0039] If desired, an internal section of generally cylindrical molding (not shown) can also be provided. This internal molding section has a diameter slightly smaller than the internal diameter of the forming opening 36. In use, the internal molding section is placed within the section of the metal fabric, for example, by manually separating the filaments of yarn from the fabric to form an opening through which the internal molding section can be passed. This internal molding section should be positioned within the tubular braid in a position where it will be disposed within the forming opening 36 of the central section when the molding element is assembled. There should be sufficient space between the external surface of the internal molding section and the internal surface of the forming opening 36 to allow the filaments of yarn 10 to be received between them.

[0040] Using this internal molding section, the dimensions of the central portion of the finished medical device can be controlled quite accurately. This internal molding section may be necessary in circumstances where the relaxed outer natural diameter of the tubular braid 10 is smaller than the internal diameter of the forming opening 36 to ensure that the braid conforms to the inner surface of the opening of training. However, it is not believed that such an internal molding section would be necessary if the relaxed outer natural diameter of the braid was larger than the internal diameter of the forming opening 36.

[0041] As indicated above, the ends of the tubular braid should be fixed in order to prevent the braid from falling apart. Each end of the metal fabric 10 is desirably received within a cavity 46 formed in one of the two end plates 40. If a fastener (15 in Figure 2) is used, the fastener can be sized to be received relatively comfortably within one of these cavities 46 in order to effectively join the end of the fabric to the end plate 40. The end plates can then be led to the central section 30 and towards each other until the compression disc 44 of each end plate is received within a central recess 34 of the central section 30. The molding element can then be fixed in position, passing bolts or the like through the channels 48 in the molding element and jointly blocking the various components of the molding element by tightening a nut on such bolt (not shown).

[0042] As best seen in Figure 3A, when an end plate is pushed towards the central section 30, this will compress the tubular braid 10 generally along its axis. When the tubular braid is in its relaxed configuration, as illustrated in Figure 1A, the strands of yarn that form the tubular braid will have a predetermined first relative orientation to each other. As the tubular braid is compressed along its axis, the fabric will tend to widen away from the axis, as illustrated in Figure 4. When the fabric deforms well, the relative orientation of the strands of tissue yarn will change. metal. When the molding element is finally assembled, the metal fabric will generally conform to the molding surface of this element.

[0043] In the molding element 20 shown in Figures 2-4, the molding surface is defined by the internal surface of the forming opening, the internal surfaces of the central recess 34 and the faces of the compression discs 44 which they are received within the recesses 34. If an internal molding section is used, the external cylindrical surface of that section can also be considered a part of the molding surface of the molding element 20. Consequently, when the molding element 20 is completely assembled, the metallic fabric will tend to assume a configuration shaped somewhat similar to "gym weights", with a relatively narrow central section arranged between a pair of bulbous end sections, perhaps even disk-shaped, as best seen in Figure 4

[0044] It should be understood that the specific form of the particular molding element 20 shown in Figures 2-4 is intended to produce a useful medical device according to the present method, but that other molding elements with different shape configurations could be used. If a more complex shape is desired, the molding element may have more pieces, but if a simpler form is configured, the molding element may have even fewer parts. The number of pieces in a given molding element and the shapes of those pieces will be dictated almost entirely by the shape of the desired medical device, since the molding element must define a molding surface to which the metallic fabric will generally adapt.

[0045] Accordingly, the specific molding element 20 shown in Figures 2-4 is simply intended to be a specific example of a molding element suitable for forming a particular useful medical device. Additional molding elements with different designs to produce different medical devices are explained below in relation to, for example, Figures 8 and 10. Depending on the desired shape of the medical device that is formed, the shape and configuration of other molding elements Specific ones can be easily designed by experts with ordinary knowledge in the art.

[0046] Once the molding element 20 is assembled with the metal fabric, generally adjusting to a molding surface of that element, the fabric can be subjected to heat treatment while remaining in contact with that molding surface. This heat treatment will depend largely on the material from which the wire filaments of the metallic fabric are formed, but the time and temperature of the heat treatment should be selected to basically fix the fabric in its deformed state, that is, in which the filaments of yarn are in their relative configuration reoriented and the fabric is generally adapted to the molding surface.

[0047] The time and temperature of the heat treatment can vary greatly depending on the material used to form the filaments of yarn. As indicated above, a preferred class of materials for forming the wire filaments are shape memory alloys, with nitinol, a nickel titanium alloy being particularly preferred. If nitiniol is used to make the yarn filaments of the fabric, the yarn filaments will tend to be very elastic when the metal is in its austenitic phase; Frequently, this very elastic phase is referred to as the "super-elastic" or "pseudo-elastic" phase. By heating the nitinol above a certain phase transition temperature, the crystalline structure of the nitinol metal can be fixed when it is in its austenitic phase. This will tend to "fix" the shape of the fabric and the relative configuration of the filaments of yarn in the positions in which they are maintained during the heat treatment.

[0048] Nitinol wire heat treatments suitable for fixing a desired shape are well known in the art. For example, nitinol helical coils are used in a number of medical applications, such as forming the coils that are commonly carried in distal sections of guidewires. There is a broad body of knowledge to form nitinol in such medical devices, so there is no need to discuss here in great detail the parameters of a heat treatment for nitinol tissue, preferred for use in the present invention.

[0049] Briefly, however, it has been found that maintaining a nitinol tissue at about 500 ° C to about 550 ° C, for a period of about 1 to about 30 minutes, depending on the softness or hardness of the device to be made , will tend to fix the fabric in its deformed state, that is to say in which it conforms to the molding surface of the molding element. At lower temperatures, the heat treatment time will tend to be longer (for example, about one hour at about 350 ° C) and at higher temperatures the time will tend to be shorter (for example, about 30 seconds at about 900 ° C ). These parameters may be varied as necessary to accommodate variations in the exact composition of nitinol, prior heat treatment of nitinol, desired properties of nitinol in the finalized article and other factors that will be well known to those skilled in this field.

[0050] Instead of relying on convection heating or the like, it is also known in the art to apply an electric current to the nitinol to heat it. In the present invention, this can be achieved, for example, by attaching electrodes to the fasteners 15, provided at either end of the metal fabric illustrated in the figure.

5. The wire can then be heated by resistance heating of the wires, in order to achieve the desired heat treatment, which will tend to eliminate the need to heat the entire molding element to the desired heat treatment temperature in order to heat the metal fabric to the desired temperature.

[0051] After heat treatment, the tissue is removed from contact with the molding element and will substantially retain its shape in a deformed state. When the molding element 20 illustrated in Figures 2-4 is used, the bolts (not shown) can be disassembled and the various parts of the molding element can be disassembled essentially in the reverse process of assembling the molding element. If an internal molding section is used, this molding section can be removed much like that used to be placed inside the generally tubular metal fabric when assembling the molding element 20, as detailed above.

[0052] Figures 5A and 5B illustrate an embodiment of a medical device 60, which can be done using the molding element 20 of Figures 2-4. As discussed above, the device of Figure 5 is particularly suitable for use to occlude a channel within a patient's body and these designs have particular advantages in their use as vascular occlusion devices.

[0053] The vascular occlusion device 60 of Figure 5A includes a generally tubular middle part 62 and two of expanded diameter parts 64. An expanded diameter part is disposed at both ends of the generally tubular middle portion, 62. In In the embodiment shown in Figures 5A and 5B, the expanded diameter portions 64 include a ridge 66 located halfway to their sections.

[0054] The relative dimensions of the middle tubular section and the expanded diameter parts may be varied as desired. In this particular embodiment, it is intended to use the medical device as a vascular occlusion device to substantially interrupt the flow of blood through a patient's blood vessel. When the device 60 is deployed within a patient's blood vessel, as detailed below, it is positioned within the vessel such that its axis generally coincides with the axis of the vessel. The shape of gym weights of the present device is intended to limit the capacity of the vascular occlusion device 60 to rotate an angle with respect to the axis of the blood vessel, to ensure that it remains basically in the same position in which the operator deploys it within the glass.

[0055] In order to fit relatively tightly into the lumen of the blood vessel, the maximum diameter of the expanded diameter portions 64 (which occurs along the middle crest 66 in this embodiment) should be selected in such a way that is at least as large as the diameter of the lumen of the vessel in which it will be deployed, and optimally slightly larger than that diameter. When implanted into the patient's vessel, vascular occlusion device 60 will fit into the lumen in two separate locations. The device 60 is desirably longer along its axis than the dimension of its larger diameter. This will substantially prevent the vascular occlusion device 60 from rotating within the lumen at an angle to its axis, basically preventing the device from moving and falling along the vessel with blood flowing through the vessel.

[0056] The relative sizes of the generally tubular middle part 62 and the expanded diameter part 64 of the vascular occlusion device 60 may be varied as desired for any particular application. For example, the outer diameter of the middle part 62 may vary between about a quarter to about one third of the maximum diameter of the expanded diameter parts 64 and the length of the middle part 62 may comprise about 20% to about 50% of the total length of the device. Although these dimensions are suitable if the device 60 is going to be used only to occlude a vascular vessel, it should be understood that these dimensions can be varied if the device is to be used in other applications, as well as if it is intended to use the device simply as a vascular filter rather than to substantially occlude the entire vessel, or for the device to be deployed in a different channel in a patient's body.

[0057] The dimension ratio (ie, the ratio of the length of the device to its maximum diameter or width) of the device 60 illustrated in Figures 5A and 5B is desirably at least about 1.0, with a preference being preferred. range from about 1.0 to about 3.0 and a dimension ratio of about 2.0 being particularly preferred. Having a higher dimension ratio will tend to prevent the device from rotating generally perpendicular to its axis, which can be called rolling. As long as the outer diameter of the expanded diameter portions 64 of the device is large enough to seat the device securely enough against the lumen of the channel in which the device is deployed, the inability of the device to rotate knocking will help maintain the device implanted precisely where it has been located within the patient's vascular system or in any other channel in the patient's body. Alternatively, having expanded diameter parts having relaxed natural diameters substantially larger than the lumen of the vessels in which the device is implanted should also be sufficient to fit the device into place in the vessel without unduly worrying about the dimension ratio of the device.

[0058] The passage and advancement of the metallic fabric 10 used to form the device 60, as well as some other factors such as the number of threads used in a tubular braid, are important in determining various properties of the device. For example, the greater the pitch and advancement of the fabric, and therefore the greater the density of the strands of yarn braided in the fabric, the more rigid the device will be. Having a higher thread density will also provide the device with a larger surface area of thread, which will generally increase the tendency of the device to occlude a blood vessel in which it is deployed. This thrombogenicity can be either increased, for example, with a coating of a thrombolytic agent, or mitigated, for example, with a coating of an antithrombogenic lubricating compound.

[0059] When the device is implanted in a patient's vessel, the thrombi will tend to accumulate on the surface of the threads. By having a higher thread density, the total surface area of the threads will increase, increasing the thrombotic activity of the device and allowing it to relatively quickly occlude the vessel in which it is deployed. It is believed that forming occlusion device 60 from a 4 mm diameter tubular braid with an advance of at least about 40 and a passage of at least about 30 ° will provide sufficient surface area to substantially completely occlude a blood vessel from 2 mm to about 4 mm inside diameter, in a suitable period of time. If it is desired to increase the rate at which the device 60 occludes the vessel in which it is deployed, any of a wide variety of known thrombotic agents can be applied to the device.

[0060] Figures 6A-6C illustrate an alternative embodiment of a medical device not in accordance with the present invention. This device 80 has a generally flared body 52 and an outwardly extending front end 84. An application for which this device is particularly suitable is to occlude defects known in the art such as central bridges or patent ductus arteriosus (PDA). PDA is basically a condition in which two blood vessels, most commonly the aorta and the pulmonary artery adjacent to the heart, have a communication between their lumens. Blood can flow directly between these two blood vessels across the bridge, compromising the normal flow of blood through the patient's vessels.

[0061] As explained more fully below in relation to Figure 8, the flared body 82 is adapted to deploy within the bridge between the vessels, while the front end 84 is adapted to be positioned within the aorta to help settle the body on the bridge. The sizes of body 82 and end 84 can be varied as desired for bridges of different sizes. For example, the body can have a diameter along its generally cylindrical middle portion 86 of about 10 mm and a length along its axis of about 25 mm. In such a device, the base 88 of the body can widen out generally radially until it reaches an outside diameter equal to that of the front end 84, which can be of the order of about 20 mm in diameter.

[0062] The base 88 desirably widens out relatively quickly to define a projection that decreases radially outwardly from the middle 86 of the body. When the device is deployed in a vessel, this protrusion will abut the lumen of the vessels treated with greater pressure. The front end 84 is retained inside the vessel and forces the base 88 of the body to open to ensure that the shoulder fits into the wall of the vessel to prevent the device 80 from being displaced from inside the bridge.

[0063] As detailed above, in making such a device it is desirable to join together the ends of the filaments of yarn that form the metallic fabric 10 to prevent the tissue from falling apart. In the illustrations of Figures 6A6C, a fastener 15 is used to tie the ends of the filaments of thread adjacent to the front end 84 of the device. However, it should be understood that this fastener 15 is simply a schematic illustration and that the ends can be joined in other ways, such as by brazing, soft welding, use of biocompatible cement material or any other suitable form.

[0064] The rear ends of the thread filaments are shown joined together by an alternative fastener 90. This fastener 90 serves the same purpose as the fastener 15 schematically illustrated, specifically to connect the ends of the threads to each other. However, the clamp 90 also serves to connect the device 80 to a carrier system (not shown). In the embodiment shown, the fastener 90 is generally cylindrical in shape and has a recess to receive the ends of the threads to fundamentally prevent the threads from moving relative to each other, and a threaded outer surface. The threaded outer surface is adapted to be received inside a cylindrical recess (not shown) at a distal end of a carrier device and to engage the threaded inner surface of the carrier device recess.

[0065] The carrier device (not shown) may take any suitable form, but desirably comprises an elongated flexible metal shaft having a recess, as mentioned, at its distal end. The carrier device can be used to drive the PDA 80 occlusion device along the lumen of a catheter for deployment in a channel of the patient's body, as described above. When the device is deployed outside the distal end of the catheter, the device will still be retained by the carrier device. Once the correct position of the device 80 on the bridge is confirmed, the axis of the carrier device can be rotated around its axis to unscrew the fastener 90 of the recess in the carrier element.

[0066] By keeping the PDA device 80 attached to the carrier element, the operator could still fold back the device to reposition it if it is determined that the device was not positioned correctly on the first attempt. This threaded joint will also allow the operator to control the manner in which the device 80 is deployed outside the distal end of the catheter. As explained above, when the device exits the catheter it will tend to return elastically to an expanded preferred form that is fixed when the tissue is heat treated. When the device elastically recovers its shape, it can tend to act against the distal end of the catheter, effectively pushing forward beyond the end of the catheter. This spring action could foreseeably result in an incorrect positioning of the device if the situation of the device within a channel is critical, such as where it is located on a bridge between two vessels. Since the threaded fastener 90 can enable the operator to hold the device during deployment, the spring action of the device can be controlled and the operator can control the deployment to ensure correct positioning.

[0067] A PDA occlusion device 80 of this embodiment of the invention can advantageously be made in accordance with the method described above, namely by deforming a metal fabric to generally conform to a molding surface of a molding element and heat treating the tissue. to substantially fix the tissue in its deformed state. Figure 7 shows a molding element 100 that may be suitable for forming a PDA occlusion device 80 such as that shown in Figures 6A-6C.

[0068] The molding element 100 generally comprises a body part 110 and an end plate 120. The body part 110 is adapted to receive and form the body 82 of the device 80, while the end plate is adapted to compressing against the metallic fabric to form the front end 84. The body part 110 includes an elongate generally tubular central segment 112 that is sized to receive the elongate body 82 of the device. The central segment 112 of the molding element 100 optimally has an internal diameter slightly smaller than the relaxed outer natural diameter of the tubular braid from which the device is formed. This braid compression will help produce devices with reproducible size bodies 82. The front end of the body part 110 includes a back plate 114 that has a wall, generally annular, side 116 and that depends on it downwards. The side wall defines a recess 118 that is generally circular in shape.

[0069] The end plate 120 of the molding element 100 has a generally disc-shaped face 122, which desirably has a fastener opening 124, centered approximately thereon, to receive a fastener 15 attached to the metal fabric, as before has indicated. The end plate also has an annular side wall 126, which generally extends upwardly from the face 122, to define a generally cylindrical recess 128 in the end plate 120. The side wall 116 of the body part 110 is sized to be received. inside recess 128 of the end plate.

[0070] In use, the metallic fabric is placed in the molding element and the body part 110 and the end plate 120 approach each other. The inner face of the back plate 114 will fit the tissue and will tend to force it under compression out generally radially. The tissue will then generally be confined within the recess 118 of the body part and will generally conform to the inner surface of that recess. If the complete fastener 15 is prevented from passing through the fastening opening 124, the fabric will separate slightly from the inner surface of the face 122, resulting in a slight dome shape at the front end 84 of the device, as illustrated in Figure 6. Although the illustrated embodiment includes such a dome-shaped front end, it should be understood that the front end can be basically flat (except for the fastener 15), which can be achieved by allowing the fastener to be fully received within the clamping opening 124 in the end plate.

[0071] Once the fabric is compressed in the molding element 100, so that it generally conforms to the molding surface of the molding element, the fabric can be subjected to a heat treatment as described above. When the molding element is opened again by separating the body part 110 and the end plate 120 from each other again, the fabric will generally retain its compressed deformed configuration. The device can then be folded, for example, forcing the fasteners 15, 90 to separate from each other generally axially, which will tend to fold the device towards its axis. The folded device 80 can then be passed through a catheter for deployment in a channel in a patient's vascular system.

[0072] Figure 8 schematically illustrates how a medical device 80, generally as described above, can be used to occlude a patent ductus arteriosus. In this case, there is a bridge, referred to earlier as a PDA, that extends between the aorta A and the pulmonary artery P of a patient. The device 80 can be passed through the PDA, such as by keeping the device folded inside a catheter (not shown), and the front end 84 of the device can be allowed to expand elastically to substantially recover its "remembered" thermally fixed form from of the heat treatment process, such as forcing the device distally to extend beyond the distal end of the catheter. This leading end 84 should be greater than the lumen of the PDA bridge.

[0073] The device can then be retracted so that the front end 84 connects to the wall of the pulmonary artery P. If the catheter continues to be retracted, the connection of the device with the wall of the PDA will tend to naturally remove the part from the catheter. of body 82 of the device, which will allow the body part to return to its expanded configuration. The body part should be sized so that it frictionally engages the lumen of the PDA bridge. The device 80 will then be held in place by the combination of friction between the body part and the bridge lumen and the aortic blood pressure against the leading end 84 of the device. In a relatively short period of time, thrombi will form inside and on the device 80 and the thrombi will occlude the PDA. Those skilled in the art will appreciate that, in order to accelerate the occlusion of the PDA or ASD device, the device may be coated with a suitable thrombogenic agent, filled with a polyester fiber or braided with an increased number of strands of yarn.

[0074] Figures 9A and 9B are a side view and an end view, respectively, of another additional device. This device 180 can be used for a variety of applications in a patient's blood vessels. For example, if a tissue with a relatively high feed is used to make the device (i.e., in which the thread density is quite large), the device can be used to occlude blood vessels. In other applications, it can serve as a filter within a channel of a patient's body, either in a blood vessel or in another channel, such as in a urinary tract or bile duct. In order to further increase or reduce the tendency of the device to occlude the vessel, adequate known antithrombogenic coverage may be applied to the device, depending on the application of the device.

[0075] This filter 180 has a generally conical configuration, generally decreasing radially outwardly from its rear end 182 to its front end 184. A section of the device adjacent to its front end is adapted to connect to the walls of A lumen of a channel. The maximum diameter of the filter device 180 is, therefore, at least as large as the inside diameter of the channel in which it is to be placed so that at least the front end will be connected to the vessel wall to basically hold the device instead.

[0076] Having a series of unsealed ends 185 of the thread filaments adjacent to the front end of the device will help to seat the device in the channel because the ends of the threads will tend to dig into the vessel wall slightly as the front end of the device is driven towards its fully expanded configuration inside the vessel. The combination of friction between the front end of the device that is driven outward and the tendency of the ends of the wire to stick inside the walls of the vessel will help ensure that the device remains in the place where it is deployed instead of floating freely inside a glass to reach an unwanted location.

[0077] The method by which the device 180 is deployed may vary depending on the nature of the physiological condition to be treated. For example, when treating an arteriovenous fistula, the device can be carefully positioned, as described above, to occlude blood flow at a fairly specific location. When treating other conditions (for example, an arteriovenous malformation), however, it may be desired to simply release a number of these devices upstream of the malformation in a vessel that has a larger lumen and simply allow the devices to drift from the treatment site to stay in smaller vessels downstream.

[0078] The decision of whether device 180 should be accurately positioned in an exact location within the channel in a patient's body or if it is more desirable to allow the device (s) to float to its final accommodation site will depend on the size of the channels involved and the specific condition to be treated. This decision should be left for the individual operator to make, based on each case, as dictated by his experience; There is no right or wrong way to deploy the device 180 regardless of the conditions of the case.

[0079] In the embodiment shown in Figures 9A and 9B, the wall of the device extends, generally linearly, from a position adjacent to the fastener 90 to the other end of the device, approaching a conical shape. However, due to the presence of the fastener 90, the end of the device immediately adjacent to the fastener may deviate slightly from the conical shape, as indicated in the drawings. Alternatively, the wall may be curved so that the diameter of the device changes more rapidly next to the rear end than next to the front end, having an appearance more like a rotation of a parabola around its main axis than a true cone. Any of these embodiments should be sufficient to occlude a vessel with the device 180, such as to occlude a vessel.

[0080] The ends of the filaments of yarn at the rear end 182 of the device are fixed to each other, such as by means of a threaded fastener 90 such as the one described above in relation to Figures 6A-6C. Parts of the wire filaments adjacent to the front end 184 can also be fixed against relative movement, for example by welding the threads to each other where they intersect near the front end. This spot welding is schematically illustrated in 186 in Figures 9A and 9B.

[0081] However, in the embodiment illustrated in Figs. 9, the ends of the thread filaments adjacent the leading end 184 in the finished device need not be fixed to each other in any way. These filaments are held in a fixed position during the formation process to prevent the metallic tissue from falling apart before it is configured in a finished device. As long as the ends of the thread filaments adjacent to the front end remain fixed with each other, they can be heat treated, as described above. The heat treatment will tend to fix the shapes of the wires in their deformed configuration in which the device generally adjusts to a molding surface of the molding element. When the device is removed from contact with the molding element, the threads will maintain their shape and tend to remain intertwined. Consequently, when the device is released from contact with the molding element, even if the ends of the threads are released from any restriction, the device should still substantially maintain its shape.

[0082] Figures 10A-10C illustrate three molds suitable for use in forming filter 180 of Figures 9A and 9B. In Figure 10A, the molding element 200 is a single piece that defines a pair of generally conical pieces that abut each other. In another similar embodiment (not shown), the molding element 200 may be generally ovoid, with a shape not unlike a football or rugby ball. In the embodiment illustrated in Figure 10A, however, the molding element is slightly less rounded. This molding element comprises two conical segments 202 that abut each other by their bases, defining a larger diameter in the middle 204 of the element that can decrease, relatively evenly, towards the ends 206 of the element 200.

[0083] When a tubular braid is used when forming this device, the tubular metallic fabric can be applied to the molding element, placing the molding element inside the tubular braid and holding the ends of the braid around the molding element before Cut the braid to the desired length. In order to better facilitate the attachment of the fasteners 90 to the ends of the tubular braid, the ends 206 of the molding element may be rounded, as shown, better than decreasing to a sharper point at the ends of the element of molding In order to ensure that the braid fits more closely to the outer surface of the molding element 200, that is, the molding surface of the molding element, the relaxed natural diameter of the braid should be less than the maximum diameter of the element, what happens in its middle zone 204. This will place the tension metal fabric around the middle area of the element and, in combination with the fasteners at the ends of the braid, will cause the braid to fit in general with the molding surface

[0084] Figure 10B illustrates an alternative molding element 210 for forming a device basically as shown in Figures 9A and 9B. While it is intended that the molding element 200 is designed to be received within a recess in the metallic fabric, such as within the lumen of a section of tubular braid, the molding element 210 has an internal cavity 212 adapted to receive the tissue. In this embodiment, the molding element may comprise a pair of molding sections 214, 216 and these mold sections may be substantially identical in shape. Each of the molding sections 214, 216 generally comprises a conical internal surface 220 defined by a wall 222. Each section may also be provided with a generally cylindrical axial recess 224 to receive a fastener 15 (or 90) carried by one end of the metallic fabric

[0085] The two molding sections should be easily joined together, with the larger open ends 226 of the sections abutting each other. The sections of the mold can simply be joined together, for example, by providing a reusable fastener (not shown) that can be used to correctly position the sections 214, 216 with each other. If so desired, through holes 228 or the like can be arranged to allow a screw and nut, or any similar joint system, to pass through the holes and join together sections 214, 216.

[0086] In practice, a piece of suitable size of a metallic fabric, optimally a section of a tubular braid, is placed in the recess 212 of the molding element and the two molding sections 214, 216 are pressed towards each other . The tissue should have a relaxed axial length longer than the axial length of the recess 212, such that bringing the sections toward each other will axially compress the tissue. This axial compression will tend to bind the strands of braid thread radially outward from the braid shaft and into a socket with the molding surface of the element 210, which is defined by the surface of the recess 212.

[0087] Once the metal fabric has been deformed to generally conform to the molding surface of any molding element 200 or 210, the fabric can be heat treated to substantially fix the shape of the fabric in its deformed state. If the molding element 200 is used, it can then be removed from within the metal fabric. If there is enough space between the elastic thread filaments, the molding element can simply be removed by opening the spider web of thread filaments and removing the molding element from the inside of the metal fabric. If the molding element 210 is used, the two molding sections 214, 216 can be separated from each other and the molded fabric can be recovered from the recess 212. Depending on the shape of the molding surface, the resulting shaped shape may resemble a pair of hollow cones facing or, as indicated above, a soccer ball, with fasteners, welds or the like, provided at either end of the configuration.

[0088] This configuration can then be cut in two halves by cutting the threads in a direction generally perpendicular to the shared axis of the cones (or the main axis of the ovoidal shape) in a position towards the middle of its length. This will produce two separate filter devices 180 essentially as illustrated in Figures 9A and 9B. If the wire filaments are to be attached adjacent to the front end of the device (such as by the welds shown as 186 in Figures 9A and 9B), this can be done before the conical or ovoidal shape is cut in two halves. Almost the same final configuration could be achieved by cutting the metal fabric in halves while still in the molding element 200. The halves separated with the desired shape could then be distanced, leaving the molding element ready to form additional devices.

[0089] In an alternative method, the molding element 200 is formed of a material selected to allow the molding element to be destroyed to remove it from inside the metal fabric. For example, the molding element may be formed of a brittle or brittle material, such as glass. Once the material has been heat treated in contact with the molding surface of the molding element, the molding element can be broken into smaller pieces that can be easily removed from within the metal fabric. If the material is glass, for example, the molding element and the metallic fabric can hit a hard surface, causing the glass to break apart. The glass fragments can then be removed from the metal tissue enclosure. The resulting form can be used in its generally conical form, or it can be cut into two separate halves to produce a device basically as shown in Figures 9A and 9B.

[0090] Alternatively, the molding element 200 may be formed of a material that can be chemically dissolved, or otherwise decomposed, by a chemical agent that does not basically adversely affect the properties of the metal wire filaments. For example, the molding element may be formed of a temperature resistant plastic resin that is capable of dissolving with a suitable organic solvent. The fabric and the molding element can be subjected to a heat treatment to substantially fix the shape of the fabric in accordance with the surface of the molding element, whereby the molding element and the metallic fabric can be immersed in the solvent. Once the molding element is substantially dissolved, the metal fabric can be removed and either used in its current configuration, or cut into separate halves, as described above.

[0091] Care should be taken to ensure that the material selected to form the molding element is able to withstand the heat treatment without losing its shape, at least until the shape of the fabric has been fixed. For example, the molding element could be formed of a material with a melting point above the temperature necessary to fix the shape of the filaments of yarn, but below the melting point of the metal that forms the filaments. The molding element and the metal fabric can then be heat treated to fix the shape of the metal fabric, whereby the temperature can be increased to melt the molding element substantially completely, thereby removing the molding element from within the fabric. metal.

[0092] It should be understood that the methods just described for removing the metallic fabric 10 from the molding element 200 can also be used in relation to other configurations. Although these methods may not be necessary or desirable if the molding element goes outside the metal fabric (such as elements 30-40 of the molding element 20 of Figures 2-4), if the molding element or any part thereof is enclosed within the formed metal tissue (such as the internal molding section of the molding element 20), these methods can be used to effectively remove the molding element without adversely affecting the medical device in formation.

[0093] Figure 10C illustrates another molding element plus 230 that can be used to form a medical device such as that illustrated in Figures 9A and 9B. This molding element comprises an external molding section 232 that defines a decreasing internal surface 234 and an internal molding section 236 with an external surface 238 in basically the same way as the decreasing internal surface 234 of the external molding section. The internal molding section 236 should be sized to be received within the external molding section, a part of the metal fabric (not shown) being disposed between the internal and external molding sections. It can be considered that the molding surface of this molding element 230, to which the fabric will generally fit, includes both the internal surface 234 of the external molding section and the external surface 238 of the internal molding section.

[0094] This molding element 230 can be used with a metallic fabric that is in the form of a tubular braid. If such a fabric is used and a fastener 15 (not shown in this drawing) or a similar fastener is provided to connect the ends of the strands of thread adjacent to one end of the device, a recess (not shown) analogous to the cavity can be provided 46 on the face of the compression disc 44 of the molding element 20 (Figures 2-4) to receive the fastener.

[0095] However, the present molding element 230 can be used quite easily with a flat woven piece of metallic fabric, as illustrated in Figure 1B. When using this fabric, a piece of tissue of the appropriate size and shape is cut; by using the molding element 230 to produce a device 180 analogous to that shown in FIGS. 9A and 9B, for example, a piece of metal fabric 10 ’generally with a disk shape can be used. The metallic fabric is then placed between the two sections 232, 236 of the molding element and the sections are moved together to deform the tissue between them. After heat treatment, the tissue can be removed and will retain basically the same shape as it had when deformed between the two molding sections.

[0096] As can be seen from the explanation of the various molding elements 200, 210 and 230 in Figures 10A10C, it should be clear that a number of different molding elements can achieve essentially the same desired shape. These molding elements can be fully housed within a closed segment of tissue and depend on the tension and / or compression of the fabric to make it generally fit the molding surface of the molding element, as with the element 200 of Figure 10A The molding element 210 of Figure 10B basically encloses the tissue within a recess in the mold and depends on the compression of the tissue (in this case, axial compression of a tubular braid) to deform the tissue to the desired configuration. Finally, the fabric can be compressed between two covering parts of the molding element to deform the fabric, such as between the two sections 232, 236 of the molding element 230 in Figure 10C. Any one or more of these techniques can be used to achieve a finished product with a desired shape.

[0097] Figures 11 and 13-15 illustrate an alternative preferred embodiment of a medical device according to the present invention for correcting an atrial septal defect (ASD). With reference to Figures 13 and 15, the device 300 in its relaxed unstretched state has two discs 302 and 304, aligned in spaced relationship, joined together by a short cylinder 306. It is proposed that this device 300 may also be very suitable to occlude defects known in the art as patent foramen ovale (hereinafter PFO). ASD is a congenital anomaly of the atrial septum characterized by a structural deficiency of the atrial septum. A bridge can occur in the atrial septum, allowing flow between the right and left atria. In large defects with significant bridges from left to right through the defect, the right atrium and right ventricle are overloaded in volume and the increased volume is expelled into a pulmonary vascular channel of low resistance.

[0098] Pulmonary vascular occlusive disease and pulmonary atrial hypertension develop in adulthood. Patients with ASD secundum with a significant bridge (defined as a ratio of pulmonary blood flow to systemic blood flow greater than 1.5) are ideally operated at five years of age or when a diagnosis is made in later years. With the arrival of the two-dimensional echocardiogram and colored flow Doppler mapping, the exact anatomy of the defect can be visualized. The default size will correspond to the selected size of the ASD device to use.

[0099] The device 300, shown in its unconfined state or relaxed in Figure 13, is adapted to be deployed within the bridge comprising an ASD or a PFO. For example, the use of the device 300 in an ASD closure procedure will be described hereinafter. Following first the constructive characteristics of the device 300, the ASD 300 occluder is sized in proportion to the bridge to be occluded. In the relaxed orientation, the metallic fabric is shaped such that two discs such as elements 302 and 304 are axially aligned and linked to each other by a short cylindrical segment 306. The length of the cylindrical segment 306 preferably approximates the thickness of the atrial septum , and is 2 to 20 mm. The proximal 302 and distal 304 discs preferably have an external diameter sufficiently larger than the bridge to avoid discoloration of the device. The proximal disk 302 has a relatively flat configuration, while the distal disk 304 is cup-shaped towards the proximal end by slightly overlapping the proximal disk 302.

[0100] The ends of this braided metal fabric device 300 are welded or held together with fasteners 308 and 310, as described above, to prevent fraying. Of course, the ends may, alternatively, be held together by other means readily known to those skilled in the art. The fastener 310 that joins the thread filaments together at the proximal end also serves to connect the device to a carrier system (see figure 11). In the embodiment shown; The fastener 310 is generally cylindrical in shape and has a recess to receive the ends of the metal fabric to essentially prevent the threads comprising the woven fabric from moving relatively between them. The fastener 310 also has a threaded surface within the recess. The threaded recess is adapted to receive and couple the threaded distal end of a carrier device 312.

[0101] The ASD 300 occlusion device of this embodiment of the invention can advantageously be made in accordance with the method described above. The device 300 is preferably made of a 0.005 inch nitinol metal mesh. The braiding of the metal mesh can be done with 28 advances per inch, at an orientation angle of about 64 degrees, using a Maypole braid with 72 thread holders. The stiffness of the ASD 300 device can be increased or reduced by changing the thread size, the orientation angle, the size of the feed, the number of thread holders or the heat treatment process.

[0102] Those skilled in the art will recognize from the foregoing explanation that mold cavities must be configured consistent with the desired configuration of the ASD device. Also, it will be recognized that certain desired configurations may require that parts of the cavities be irregular. Figures 17 and 18 illustrate an ASD device according to the invention having a modified configuration. The proximal disk 302 is a mirror image of the distal disk 304. The distance between the proximal and distal discs 302 and 304 is less than the length of the cylindrical segment 306. The disk cup shape, as illustrated in Figures 13, 14, 16 and 17, ensures full contact between the occlusion device 300 and the atrial septum. Accordingly, an endothelial layer of neo endocardium is formed on occlusion device 300, thereby reducing the possibility of bacterial endocarditis.

[0103] Next, in relation to Figures 11, 14-16 and 18, the use of the device will now be discussed in greater detail. The device can be properly delivered and placed using two-dimensional echocardiography and colored flow Doppler mapping. As indicated above, the carrier device 312 may take any suitable form, preferably comprising an elongated flexible metal shaft similar to a conventional guidewire. The carrier device 312 is used to advance the ASD 300 occlusion device through the lumen of a small diameter cylindrical tube 314, such as a carrier catheter, for deployment. The ASD device 300 is loaded into the small diameter cylindrical tube 314 by stretching it to put it in an elongated state. The device can be inserted into the lumen of tube 314 during the procedure or pre-assembled in a manufacturing facility, because the devices of the present invention do not take a permanent form when they are kept in a compressed state.

[0104] From a femoral vein approach, the catheter or carrier tube 314 is passed through the ASD. The device 300 is advanced along the carrier catheter until the distal end 304 is no longer retained upon exiting the catheter end, thereby assuming its disk shape in the left atrium. The carrier catheter 314 is then removed in the proximal direction along the ASD and the carrier device 312 is pulled in the same way, in a proximal direction, forcing the distal disc 304 against the partition 318. The carrier catheter 314 is then removed additionally, separating it from the partition 318, allowing the proximal disc 302 to extend out of the carrier catheter 314, where it elastically returns to its predefined form of expanded disc (see Figure 15). Thus, the ASD device 300 is positioned such that the distal disc 304 presses against one side of the partition 318 while the proximal disk 302 presses against the other side of the partition 318. In order to increase its occlusive capacity, the device It may contain 316 polyester fibers (see Figures 15 and 18). In examples where the device is incorrectly deployed in a first attempt, the device 300 can be recovered by removing the carrier device 312 proximally, thereby removing the device 300 back to the carrier catheter 314, before a second attempt to position the device 300 with respect to to default.

[0105] When the ASD 300 occlusion device is correctly positioned, the doctor rotates the carrier device 312, unscrewing the carrier device 312 from the fastener 310 of the occluder device 300. The threading of the fastener 310 is such that the rotation of the carrier device 312 unscrews the carrier device 312 from the fastener 310 of the occluder device 300, rather than merely rotating the occluder device 300. As indicated above in alternative embodiments, the threaded fastener can enable the operator to maintain a fastener of the device during the deployment, or enables the operator to control the spring action during the deployment of the device to ensure correct positioning.

[0106] Generally, the method also includes a method of treating a physiological condition of a patient. According to this method, a suitable medical device is selected to treat the condition, which may be substantially in accordance with one of the previously described embodiments. For example, if a patent ductus arteriosus must be treated, the PDA 80 occlusion device can be selected from Figures 6A-6C. Once the appropriate medical device is selected a catheter can be placed within a channel in a patient's body to place the distal end of the catheter adjacent to the desired treatment site, such as immediately adjacent (or even within) the bridge of the PDA

[0107] Medical devices made according to the method described above have a preset expanded configuration and a folded configuration that allows the device to be passed through a catheter (see Figure 12). The expanded configuration is generally defined by the shape of the medical tissue when it is deformed to generally conform to the molding surface of the molding element. The heat treatment of the metallic fabric essentially sets the thread filament configurations in the relative reoriented positions when the fabric adjusts to the molding surface. When the metallic tissue is then removed from the molding element, the tissue can define a medical device in its preset expanded configuration.

[0108] The medical device can then be folded into its folded configuration and inserted into the lumen of the catheter. The folded configuration of the device can be of any form suitable for easy advancement along the lumen of a catheter and a correct deployment outside the distal end of the catheter. For example, the devices shown in Figures 5A-5B, 6A-6C, and 13 may have a relatively elongated folded configuration in which the devices are stretched along their axes (see Figures 11 and 12). This folded configuration can be achieved by stretching the device generally along its axis, for example, by manually holding the fasteners 15 and separating them, which will tend to fold the expanded diameter portions 64 of the device 60 inwards, towards the axis of the device. The PDA occlusion device 80 of Figs. 6 also functions very similarly and can be folded to its folded configuration for insertion into the catheter by applying tension generally along the axis of the device. In this regard, these devices 60 and 80 are not different from "Chinese wives", which tend to narrow in diameter under axial tension.

[0109] Once the medical device is folded and inserted into the catheter, it can be conducted along the lumen of the catheter to the distal end of the catheter. This can be achieved using a guidewire or similar to butt against the device, and propel it along the catheter. When the device begins to exit the distal end of the catheter, which is located adjacent to the desired treatment site, it will tend to return elastically essentially completely to its predetermined expanded configuration. Super-elastic alloys, such as nitinol, are particularly useful in this application because of their ability to easily return to a particular configuration after being greatly elastically deformed. Hence, simply pushing the medical device out of the distal end of the catheter tends to correctly deploy the device at the treatment site.

[0110] Although the device will tend to return elastically to its initial expanded configuration (ie, its pre-folded form to pass along the catheter), it should be understood that it may not always return completely to that form. For example, the device 60 of Figure 5 is intended to have a maximum outside diameter in its expanded configuration at least as large as, and preferably greater than, the inner diameter of the lumen in which it is to be deployed. If such a device is deployed in a vessel that has a small lumen, the lumen will prevent the device from fully returning to its expanded form. However, the device would be deployed correctly because it would connect the inside of the lumen wall to seat the device on it, as detailed above.

[0111] If the device is to be used to permanently occlude a channel in the patient's body, such as devices 60 and 80 described above, the catheter can simply be retracted and removed from the patient's body. This will leave the medical device deployed in the patient's vascular system so that it can occlude the blood vessel or other channel in the patient's body. In some circumstances, the medical device may be attached to a carrier system such that it fixes the device to the end of the carrier element, such as when the threaded fastener 90, shown in Figures 6 and 9, is attached to a distal end of the element. carrier, as explained before. Before removing the catheter in this system, it may be necessary to separate the medical device from the carrier element before removing the catheter and said carrier element.

[0112] Although a preferred embodiment of the present invention has been described, it should be understood that various changes, adaptations and modifications can be made without leaving the scope of the appended claims.

Claims (9)

1. Folding medical device (300), comprising a plurality of metallic threads that form a braided metallic tubular fabric (10) having a preset expanded configuration, the ends of the tubular braiding threads being held in order to prevent the frayed threads, wherein said medical device is configured to create an occlusion of an abnormal opening in a cardiac septal wall, according to which said preset expanded configuration is deformable by adopting a smaller transverse dimension for transport by means of a channel in the a patient's body, the woven metal tissue having a memory property such that the medical device tends to return to said preset expanded configuration when it is not constrained, the preset expanded configuration comprising a first and second expanded diameter parts (302, 304), respectively, at the distal and proximal ends of the device and a reduced diameter part (306) disposed between the two expanded diameter parts, said said part of reduced diameter a dimension of length that approximates a thickness of the septal wall in the abnormal opening, in which at least one of said first and second parts of expanded diameter is cup-shaped towards the other of the parts of diameter expanded, causing, in use, that the perimeter edge of the expanded cup-shaped diameter part connect completely with the sidewall of the partition, the foldable medical device further including an occlusion fiber (316) retained within said woven tubular tissue.

2.

Medical device (300) according to claim 1, wherein said preset expanded configuration has a shape of gym weights.

3.

Medical device (300) according to claim 1, further including elements for fastening the ends of the threads of the tubular braid, said fasteners including a thread for connection by rotation to a carrier device.

Four.

Medical device (300) according to claim 1, wherein the metallic fabric is manufactured from an alloy selected from the group consisting of stainless steel, nickel-titanium and cobalt-chromium-nickel.

5.

Medical device (300) according to claim 1, wherein the part of reduced diameter (306) has a length dimension of between 2 to 20 millimeters.

6.

Medical device (300) according to claim 1, wherein the occlusion fiber comprises polyester fibers (318).

7.

Medical device (300) according to claim 1, further including means for securing the threads of the tubular braid at one end of the device.

8.

Medical device (300) according to claim 7, wherein the means for securing one end of the device comprise a fastener (90).

9.

Medical device (300) according to claim 1, said occlusion fiber (316) comprising both of said first and second expanded diameter parts (302, 304).